Enhanced removal of U(VI) by SnS2/NiCr-LDH under humic acid: synergistic effect and removal mechanism

In this study, tin sulphide (SnS 2 ) and nickel–chromium hydrotalcite (NiCr-LDH) complexes (SnS 2 /NiCr-LDH) were used for the simultaneous removal of U(VI) and humic acid (HA) from U(VI)-containing wastewater. The results showed that the adsorption of HA by the SnS 2 /NiCr-LDH was greatly enhanced, which was 4.07 and 2.94 times higher than that of pure SnS 2 and NiCr-LDH, respectively, and the highest U(VI) adsorption quantity over SnS 2 /NiCr-LDH increased from 127.81 to 446.68 mg g −1 when HA was present. Density functional theory (DFT) calculations revealed that the enhanced U(VI) adsorption on SnS 2 /NiCr-LDH was facilitated by the formation of a robust inner-sphere surface complex between U(VI) and HA.